ExchangeService.AutodiscoverUrl fails

[Krimsondk]

Since moving our Exchange installation to Office 365 the ExchangeService.AutodiscoverUrl (from within EWSConnectionManger.ConnectToEWS) call have started to fail. I get the following exception:

System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
at System.Collections.ArrayList.get_Item(Int32 index)
at System.DirectoryServices.ResultPropertyValueCollection.get_Item(Int32 index)
at Microsoft.Exchange.WebServices.Autodiscover.DirectoryHelper.GetScpUrlList(String domainName, String ldapPath, Int32& maxHops)
at Microsoft.Exchange.WebServices.Autodiscover.DirectoryHelper.GetAutodiscoverScpUrlsForDomain(String domainName)
at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.GetAutodiscoverServiceUrls(String domainName, Int32& scpHostCount)
at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.GetAutodiscoverServiceHosts(String domainName, Int32& scpHostCount)
at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.GetSettings[TGetSettingsResponseCollection,TSettingName](List1 identities, List1 settings, Nullable1 requestedVersion, GetSettingsMethod2 getSettingsMethod, Func1 getDomainMethod) at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.GetUserSettings(List1 smtpAddresses, List1 settings) at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.InternalGetSoapUserSettings(String smtpAddress, List1 requestedSettings)
at Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService.GetUserSettings(String userSmtpAddress, UserSettingName[] userSettingNames)
at Microsoft.Exchange.WebServices.Data.ExchangeService.GetAutodiscoverUrl(String emailAddress, ExchangeVersion requestedServerVersion, AutodiscoverRedirectionUrlValidationCallback validateRedirectionUrlCallback)
at Microsoft.Exchange.WebServices.Data.ExchangeService.AutodiscoverUrl(String emailAddress, AutodiscoverRedirectionUrlValidationCallback validateRedirectionUrlCallback)
at Mail2Bug.Email.EWS.EWSConnectionManger.ConnectToEWS(Credentials credentials, Boolean useConversationGuidOnly) in C:\Projects\GitHub\mail2bug\Mail2Bug\Email\EWS\EWSConnectionManger.cs:line 91
at Mail2Bug.Email.EWS.EWSConnectionManger.GetConnection(Credentials credentials, Boolean useConversationGuidOnly) in C:\Projects\GitHub\mail2bug\Mail2Bug\Email\EWS\EWSConnectionManger.cs:line 61
at Mail2Bug.Email.MailboxManagerFactory.CreateMailboxManager(EmailSettings emailSettings) in C:\Projects\GitHub\mail2bug\Mail2Bug\Email\MailboxManagerFactory.cs:line 31
at Mail2Bug.Mail2BugEngine..ctor(InstanceConfig configInstance, MailboxManagerFactory mailboxManagerFactory) in C:\Projects\GitHub\mail2bug\Mail2Bug\Mail2BugEngine.cs:line 31
at Mail2Bug.MainApp.InitInstances(IEnumerable`1 configs) in C:\Projects\GitHub\mail2bug\Mail2Bug\Main.cs:line 214

I can replicate this by newing up a ExchangeService and calling AutodiscoverUrl outside Mail2Bug.

If I use the Microsoft.Exchange.WebServices.Autodiscover.AutodiscoverService class instead, then I can get the URL to the mailbox, which I can use to set the ExchangeService.Url property and this works.

Would it be possible to have a setting which specifies that the AutodiscoverService class should be used instead of the AutodiscoverUrl method?